WASHINGTON — Keystone XL is clearly the party that U.S. President Barack Obama doesn’t want to attend.

For years now he has been dodging persistent invitations hand-delivered by Prime Minister Stephen Harper and a parade of cabinet ministers and western premiers as well as plastered across the walls and floors of Washington subway stations in the form of ads promoting U.S.-Canada friendship and energy security.

Obama’s reply has been to delay, which he did again last week. And once again the excuse was Nebraska.

Back in February when a Nebraska judge ruled the state’s process for approving the pipeline’s route was illegal, the U.S. State Department dismissed it as immaterial to the assessment process. Then Obama surprised everybody last week by using it as an excuse to postpone his final decision.

That Nebraska was once again little more than a convenience is significant. Obama’s decision on Keystone is about whether it’s in the national interest of the United States to allow this pipeline to cross the border. It’s not about whether the route through Nebraska is safe or whether the Nebraska process for approving that route was legal. That, in the end, is for Nebraska to decide. Obama could easily have approved the pipeline and left Nebraska to settle its section of the route.

But he didn’t. Instead, he followed conventional wisdom that a “Yes” to Keystone would discourage his environmentalist youth base and a “No” would give fodder to Republicans who would label him a job-killer.

Faced with increasing pressure to make a decision in May, he chose to side with his advisers that he had nothing to lose by another delay. Democrats fear the loss of just three seats could lose them the Senate in November. Keystone could tip the balance in oil states such as Louisiana, where the Democrat senator faces a tight race. Whether the fate of a Canadian oil pipeline would determine an election in parochial America is doubtful. But why take the chance?

In the end, a delay doesn’t bother environmentalists. “Every day that the pipeline is not built is good for the environment,” Ross Hammond, a senior campaigner for Friends of the Earth, said in an interview. “What counts is his final decision and I believe he’ll deny the permit.”

This is no easy political game. The pipeline has assumed the role of the big bad guy of climate change in a country that still entertains powerful doubts about the issue.

That was made clear yet again by an Associated Press poll released Tuesday — Earth Day — showing that only 33 per cent of Americans are very confident that the Earth’s temperatures are rising because of man-made greenhouse gases. An even larger percentage — 38 — have no confidence in the science at all and the rest are only “somewhat confident” the science is accurate.

Edward Maibach, director of the Center for Climate Change Communications at George Mason University, whose polls mirror these results, blames the inability of scientific experts to clarify their message enough to penetrate the fog of disinformation.

“Over half of Americans don’t known what the experts have concluded, which means in my opinion the experts haven’t been very effective in sharing with the public what they have concluded,” he said. “People are told there is a lot of disagreement among the scientists and therefore it would be irresponsible to take action when the science isn’t yet settled.”

Obama is a climate change president. Every statement he has ever made on the issue indicates that were he not saddled with a divided Congress and public, he would have long ago launched a national climate program promoting clean energy and sidelining fossil fuels, particularly the really dirty kind such as heavy oil from the oilsands. This would have meant an early “No” on Keystone XL, as one administration consultant said in an interview.

So, Obama is caught playing a political game over a vital issue that demands immediate action.

The irony is that Maibach’s research also shows that politicians who campaign on climate change action “are more likely to keep their job next time than lose it.”

But clearly Obama has decided there’s just no winning on this issue right now.

Whatever happens in November’s elections, he will be free to make a quick Keystone decision, own it and not burden his successor with it.

Keystone supporters should take no comfort in that. Given Keystone’s enormous symbolic significance, his decision will be a defining moment. As he heads for the exit, Keystone likely will be his ultimate message to the world — and to Canada’s Conservative government — on climate change.

If he is true to his word, it’s hard to believe that the decision will be anything other than “No.”